Cancrinite is a well-known natural zeolite having a SiO.sub.2 :Al.sub.2 O.sub.3 ratio of two which is readily synthesized in systems consisting of Na.sub.2 O-SiO.sub.2 -Al.sub.2 O.sub.3 -H.sub.2 O in the presence of a large variety of salts. See, for example, Barrer et al., J. Chem. Soc. A, 1523 (1970). In addition, U.S. Pat. No. 3,433,736 discloses hydroxyparacancrinite of the formula 3(Al.sub.2 O.sub.3, 2SiO.sub.2, Na.sub.2 O) 2NaOH from a mixture of silica, aluminum hydroxide and water. The main characterizing feature of cancrinite is a single 12-ring channel parallel to the `c` axis as described by Jarchow, Zeit Krist., 122, 407 (1965) and Pahor et al., Acta Cryst., B38, 893 (1982). Because this channel is invariably faulted or blocked by salt molecules, the structure tends to have very poor sorption properties, even when attempts are made to remove the excess salt molecules (see Barrer and Vaughan, J. Phys. Chem. Solids, 32, 731 (1971)). The synthesis chemistry has been reviewed at great length by Barrer, Hydrothermal Chemistry of Zeolites, Academic Press (1982), Ch. 7.
If the channel of the cancrinite could be unblocked, the cancrinite would be expected to be a highly active catalyst (as are other zeolites having 12-ring channel systems) such as mordenite and offretite for cracking, hydrocracking and hydrodewaxing, and mordenite and zeolite L for hydroisomerization and reforming.
Although the synthetic analog of the zeolite cancrinite is easy to produce and is otherwise well-characterized, it always has an Si/Al ratio at unity, whether in its natural state or synthesized in a wide variety of systems, and such materials have very poor sorption properties and no catalytic activity.
In the present invention, Li-Na and Li-Na-TMA forms of ECR-5 (U.S. Pat. No. 4,717,560) have been made in non-ammonia systems for the first time. ECR-5 is a high silica, porous form of the mineral cancrinite, natural and synthetic forms of which have only previously been made at an Si/Al ratio of unity, and which have no sorption capacity for organic molecules. The main interest of this structure is that it has a structure analogous to those for L, offretite, mordenite and mazzite, which have considerably value as catalysts in reforming, hydrodewaxing and hydroisomerization. This is a new and easier synthesis than that previously used for ECR-5 in that no ammonia is used in the synthesis, and therefore a major pollutant is removed from the process effluent. The product ECR-5 materials have good hydrocarbon sorption properties, ECR-5 is unusual as a 12-ring structure, in that the puckering of the 12-ring causes a narrowing of the channel to make it closer to the diameter of 10-ring structures, such as ZSM-5, ZSM-11, ferrierite, ZSM-23, etc. Such materials are known to have good catalytic properties by virtue of their high degree of shape selectivity for specific substituted aromatics (e.g., para-xylene) and branched paraffins. Therefore the structure of ECR-5 may make it a more selective catalyst than other analogous channel structures, such as mordenite or offretite.